Now, in the words of Sen. Saxby Chambliss (R-Ga.), come warnings of a potential attack that are "very reminiscent of what we saw pre-9/11." That threat has resulted in the closure of 22 embassies and consulates across the Middle East and North Africa, as well as a month-long security advisory for Americans traveling abroad.

As criticism of the NSA, fueled by the classified documents leaked by Edward Snowden, builds in the United States and overseas, the agency's supporters are pointing to intercepted intel on these possible attacks as Exhibit A in why the NSA's programs are vital to American security.

"Al Qaeda is on the rise in this part of the world and the NSA program is proving its worth yet again," Sen. Lindsey Graham (R-S.C.) told CNN's State of the Union.

This is a good indication of why they're so important. To the members of Congress who want to reform the NSA program — great. But if you want to gut it, you make us much less safe, and you're putting our nation at risk. We need to have policies in place that can deal with the threats that exist, and they are real, and they are growing. [NBC News]

Critics of the NSA's surveillance program, however, were not convinced.

"If you look at the one that's most at issue here, and that's the bulk metadata program, there's no indication, unless I'm proved wrong later, that that program, which collects vast amounts of domestic data, domestic telephony data, contributed to information about this particular plot," Rep. Adam Schiff (D-Calif.) said on CNN.

It's not entirely clear where information about this newest threat came from, though McClatchy cited an unnamed source who claims U.S. intelligence intercepted communications between al Qaeda leader Ayman al Zawahiri and Nasir al-Wuhayshi, head of the Yemen-based al Qaeda in the Arabian Peninsula.

"It's precisely because we live in this dangerous world that we need protections like the Fourth Amendment to the Constitution," Amash said. "The framers of the Constitution put it in place precisely because they were worried you'd have national security justifications for violating people's rights."